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6 Answers

Angle of Incidence is not controllable?

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My private test prep says "The pilot has no control over the angle of incidence" and I cannot understand this unless AOI means an angle in a specific configuration which I failed to find any reference mentioning so. Please enlighten me and I appreciate your help. My understanding is as follows. 1. Angle of incidence is angle between the wing chord line and the center line of the fuselage. 2. Chord line is a straight reference line from the leading edge to the trailing edge of an airfoil and changing the shape of an airfoil by lowering flaps would change the chord line. ∴ Pilot can control AOI since pilot can control chord line by lowering flaps.

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6 Answers

  1. Wes Beard on Apr 26, 2015

    The angle of incidence is the angle between the fuselage chord line and the wing chord line. It is attached by the manufacturer. It’s the angle to which the wings are attached to the fuselage.

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  2. Seokhyun Lee on Apr 27, 2015

    I understand wing chord line is controllable by lowering flaps. If wing chord line is changeable then isn’t AOI also controllable since AOI is the angle between wing chord line and fuselage chord line?

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  3. Wes Beard on Apr 27, 2015

    Part of the wing chord line is modified by the flaps. Don’t think of it like that though. Imagine the wing chord line without flaps and that angle is the angle of incidence. The angle the wing is attached to the fuselage.

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  4. Best Answer

    Kris Kortokrax on Apr 28, 2015

    You are working too hard at confusing yourself.

    Many wings attached to aircraft have washout. This is a twist which gives a lower angle of incidence at the tip than at the root. You would also need to take into account that ailerons also change the chord line.

    Just forget all this and think of the angle of incidence as the angle between the flaps up chord line at the wing root and the longitudinal axis of the airplane.

    You will be much more concerned with angle of attack than angle of incidence when in flight. The angle of attack directly affects the coefficient of lift which is one of the terms in the lift equation.

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  5. Russ Roslewski on Apr 28, 2015

    True controllable-incidence wings are pretty rare, so the confusion in terminology is not surprising. I think it will make it clear if you look at pictures of the F-8 Crusader on wikipedia:


    In this airplane, the entire wing was tipped up for takeoff and landing. Compare the pictures of it in flight and on the ground – you’ll easily see the difference at the leading edge of the wing/fuselage section. THAT’s a controllable-incidence wing.

    Flaps, while yes, they change the average chord of the wing and therefore the actual angle of incidence, aren’t really the same thing. It’s more of a terminology issue than anything else.

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  6. Tony on Jul 24, 2016

    Congratulations, none of you have answered his question as I have the same one.

    My study material and flight books mention that the angle of incidence CANNOT be changed, as it is mounted that way at manufacturing.

    My PPL exam question is as follows:

    The angle of incidence on a Cessna 172 can be changed by
    1. banking at angles greater than 45 degrees
    2. raising the aircraft\’s nose
    3. lowering the flaps
    4. adjusting the vertical trim

    ANSWER – according to exam is 3. – lowering the flaps CAN change the angle if incidence. while all reference material says the AOI cannot be changed.
    so as the original poster of this discussion set out to determine….. WHICH IS IT???

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